Transversely sealed container

ABSTRACT

The disclosure is directed to a polyethylene or similar flexible package having a maze vent to allow the escape of air from the interior of the package filled with powdered or granular material. The maze vent comprises an interior vented seal gap, a maze vent channel, and a channel vent. The maze vent allows air to escape during the filling process while maintaining the powdered or granular material within the bag and preventing ingress of air, moisture and other contaminants. The disclosure is directed to a such a package by itself or as a liner to a multiple paper ply satchel bottom bag, the poly liner being free within the innermost ply except for attachment at the mouth of the bag. Further, the satchel bottom bag of the present disclosure may contain a reinforcing patch on the satchel bottom. Additionally, the reinforcing patch may have an opener for easy opening of the bag.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e) from U.S. Provisional Patent Application No. 60/601,944, filed on Aug. 16, 2004.

BACKGROUND OF THE DISCLOSURE

The present disclosure generally relates to an improved plastic bag for use by itself or for use as a liner in conjunction with a bag having multiple paper ply construction.

More specifically, the disclosure is directed to a seamless tubular plastic liner for a multilayer satchel bottom type bag. Such bags are known in the art, an example being disclosed in U.S. Pat. No. 5,553,943 which is herein incorporated by reference. Satchel bottom bags are formed by folding a plurality of layers of kraft paper into a tube. The layers are arranged in stepped configuration for adhesive bonding. A plastic liner or pouch is inserted into the tube and secured by adhesive to the top, or the mouth end of the tube.

Plastic lined multilayer paper bags are used to package bulk granular or powdered products such as flour, corn meal, sugar, powdered milk, and similar commodities as well as other powdered or granular materials. The plastic liner may be either an additional plastic ply bonded to the inner most paper ply, or a free-floating plastic bag-within-a-bag as described herein.

Plastic bags made of polyethylene or other polymeric materials are common packaging containers for a variety of products and commodities. Such bags may be used either by themselves or as liners for paper bags. The manufacturer of the bags seals one end of the bag (called the “manufacturer end” or “plant end”) which forms the bottom seal of the bag when the bag is in use. The other end (called the “customer end”) is left open for the purchaser of the bag to fill with its product and close and seal. The customer end forms the top end of the bag through which material is introduced into the interior of the bag.

When a polyethylene bag is filled with powdered or granular material and sealed, air or other gases may become trapped in the bag. This can create air pockets in the bag, which if not allowed to escape, can result in problems when the bags are stacked for shipment. For example, trapped air prevents the bag from conforming to the powdered or granular contents creating air pockets. As bags are placed on top of each other, such as for shipment on pallets, the air bubbles make the stack of bags unstable and prone to tipping, thus limiting the number of bags that can be stacked for shipping. Also, as additional bags are placed on top of the bag containing the trapped air, the air pockets are compressed due to the additional weight, increasing the pressure inside the bag. If enough weight is placed on the bag with the trapped air, the increased air pressure may rupture the bag, resulting in spillage of the contents. Therefore venting the air from the bag facilitates stacking of bags for shipment and reduces the risk of bag rupture.

Alternatively, venting of the plastic bag may not be desirable in all situations, particularly when the contents are toxic or hazardous, such as various types of chemicals. In this situation, reinforcement of the seals is required to minimize the possibility of rupture during transportation and handling.

More particularly, the present disclosure relates to a seamless polyethylene, or similar polymer material bag, that has a maze vent allowing air to escape after the bag has been sealed while inhibiting the ingress of air, moisture and other contaminants. Such vents are known in the art and typically consist of one or more heat seals having a gap. The heat seals bond the front and rear walls of the bag together. For example, U.S. Pat. No. 6,491,433 teaches three heat seals, each with a gap being offset from the gap in the adjacent seal or seals.

One method of manufacturing a vented seal bag is typically accomplished by folding a sheet of polyethylene or similar material into a tube. When the sheet is folded, overlapping edges form a longitudinal seam in what is typically the back of the bag. The overlapping edges are then sealed with a plurality of interrupted heat seals. The interruptions in the heat seals are offset from the interruption in adjacent heat seal or seals, forming a tortuous path from the interior of the bag to the exterior, allowing trapped air to be expelled. See U.S. Pat. No. 6,170,985.

These longitudinal seams are prone to failure, causing leakage and contamination of the material contained within the bag.

The present state of the art uses a flat film that is folded to create bags with seams along the longitudinal axis of the bag that incorporate a vent. These seams are prone to failure, resulting in spilled product and associated wasted expense.

SUMMARY OF THE DISCLOSURE

This disclosure may be described as a novel and improved plastic liner and multilayer paper satchel bottom bag incorporating such a liner. The plastic (or “poly”) liner may be used by itself as an independent package, or may be incorporated as part of a bag-within-a-bag. The poly liner is placed within a multilayer paper satchel bottom bag for added strength and protection.

The poly liner is formed from a seamless tube of polyethylene or similar polymer material folded flat forming a front panel and a rear panel. A plurality of heat seals are made across the bottom of the plastic tube transverse to the direction of the bag. In one embodiment, a first solid heat seal and a second interrupted heat seal are created across the bottom or satchel end of the bag, sealing the bottom of the liner and forming a vent channel between the heat seals. The interruption in the second heat seal forms the vented seal gap. The vented seal gap is in communication with the interior space of the bag. Next, one or both of the front and rear panels of the liner are perforated within the vent channel between the heat seals with a plurality of perforation holes forming the exterior vent.

When the bag has been filled and sealed, an increase in pressure within the bag will cause the front and rear panels of the vent channel to separate allowing air to pass through the vented seal gap, through the vent channel, and to be exhausted through the exterior vent. When pressure has been reduced through venting, the front and rear panels of the vent channel collapse against each other, closing off the passage to the exterior of the bag and thus sealing the bag against entry of moisture or other contaminants from the outside.

In alternative embodiments, maze blocks may be formed within the maze vent channel, substantially perpendicular to and in communication with one or more of the transverse heat seals. The maze blocks function to form a tortuous path through the vent channel trapping powdered or granular product that may enter the vent channel. Product is retained in the vent channel preventing clogging of the exterior vent and/or leakage of product.

A machine known in the art, a W&H Rotaliner, is modified to manufacture bags having the maze vent described herein. The typical Rotaliner has a drum with a sealing bar having a sealing surface. The sealing bar is modified by machining a gap in the sealing surface corresponding to the second heat seal to create an interruption in the second heat seal forming the vented seal gap. If a bag is to be manufactured having maze blocks, weld beads are created on the Rotaliner sealing bar in communication with and substantially perpendicular to either the first or second heat seal and machined.

Under certain circumstances, venting of the plastic liner may not be desirable. It is, therefore, necessary to reinforce the bottom heat seal to prevent rupture. Multiple solid heat seals are provided at the bottom of the liner, instead of one interrupted heat seal and one solid heat seal.

In one embodiment of this disclosure, it is envisioned that a plastic liner of the type described herein is used in conjunction with a satchel bottom bag constructed of a plurality of paper layers or plies, such as kraft paper or high performance paper as is generally known in the art. A plurality of paper plies are folded into a tube wherein a plastic liner is inserted into the tube and secured by adhesive to the innermost ply near the top or mouth end.

The plastic liner is heat sealed at its bottom, or satchel end, before insertion into the paper tube. The plastic liner is also temporarily secured by adhesive to the inner paper ply of the back wall of the bag. This is to secure the liner during the satchel folding process.

The paper plies are folded to form a flat satchel bottom. After bulk product is introduced into the bag, the mouth of the plastic liner may be heat sealed closed. The paper plies at the mouth end have a stepped configuration for adhesive bonding. The paper plies are folded over and secured by adhesive, thus enclosing the plastic liner and its contents.

The satchel end of the plastic liner is folded within but not adhesively secured to the folds of the plies of the satchel end. The liner is thus secured and held flat during transport of the bag. As the bag is unfolded for filling, the plastic liner is released from the folds of the satchel end and is a free-floating bag-within-a-bag secured only at the top to the innermost paper ply.

In another embodiment of the present disclosure, a patch is provided on the outside of the folded satchel bottom. The patch may be made of kraft paper or other suitable material and may be of one or more layers and is adhesively affixed to the outside of the satchel bottom. The patch provides additional reinforcement to the satchel bottom.

In yet another embodiment, it may be desirable to provide an easy opening bottom to the bag of the present disclosure. In this embodiment, no adhesive is applied to the flaps of the satchel bottom. A patch is adhesively applied to the outside of the satchel bottom. An opener strip is provided between the patch and the flaps of the satchel bottom. The opener strip terminates at a cuff area at one side of the patch. A pair of slits are provided in the patch on either side of the opener strip to form the cuff. The opener strip may be formed of plastic, string, or other strong flexible material. A user grips the cuff pulling away from the satchel bottom. As the user pulls the cuff, the opener strip tears the patch exposing the satchel flaps which are easily opened because there is no adhesive securing them in place.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of a poly bag having a maze vent of the present disclosure;

FIG. 2 is a view of a poly bag having another embodiment of a maze vent of the present disclosure with maze blocks perpendicular to the heat seals;

FIG. 3 is a view of a poly bag of the present disclosure having a double bottom seal;

FIG. 4 a is an alternate configuration for the maze vent of the present disclosure;

FIG. 4 b is another alternate configuration for the maze vent of the present disclosure;

FIG. 4 c is another alternate configuration for the maze vent of the present disclosure;

FIG. 4 d is another alternate configuration for the maze vent of the present disclosure;

FIG. 4 e is another alternate configuration for the maze vent of the present disclosure;

FIG. 4 f is another alternate configuration for the maze vent of the present disclosure;

FIG. 4 g is another alternate configuration for the maze vent of the present disclosure;

FIG. 4 h is another alternate configuration for the maze vent of the present disclosure;

FIG. 4 i is another alternate configuration for the maze vent of the present disclosure;

FIG. 4 j is another alternate configuration for the maze vent of the present disclosure;

FIG. 4 k is another alternate configuration for the maze vent of the present disclosure;

FIG. 5 is a perspective view of the multi-ply plastic lined bag with satchel bottom, partially broken away, and having a pinch closure-type open top ready to be filled by a user with a commodity or the like;

FIG. 6 is a front elevation view of a multi-layer bag blank showing a main fold line and slits for forming a satchel bottom;

FIG. 7 is a front elevation view of a tube blank with the multiple paper plies at one side of the being folded upwardly around the main score line to thereby define upper and lower paper flaps and four diagonal bend lines in the paper ply flaps, both above and below the main score line, and foldably holding at the upper flap the plastic liner;

FIG. 8 is a detailed view of the folds of the satchel bottom;

FIG. 9 is a detailed view of the folds of the satchel bottom of a bag having an easy opening feature;

FIG. 10 is a detailed view of the completed satchel bottom with reinforcing patch.

DETAILED DESCRIPTION

While the present disclosure will be described fully hereinafter with reference to the accompanying drawings in which a particular embodiment is shown, it is understood at the outset that persons skilled in the art may modify the disclosure herein described while still achieving the desired result of this disclosure. Accordingly, the description which follows is to be understood as a broad informative disclosure directed to persons skilled in the appropriate arts and not as limitations of the present disclosure.

FIG. 1 depicts the arrangement of an embodiment of the present disclosure. A poly bag 10 is formed from a seamless tube of polyethylene or similar polymer material creating an interior and exterior. The tube is folded upon itself forming a first edge fold 12 and a second edge fold 14 and a front wall and a rear wall. When the seamless tube is cut to the desired size, it will have two ends. The first end 16, called the manufacturer end or the plant end, is typically the bottom of the bag. The second end 18, called the customer end because the bag purchaser seals this end after it fills the bag with product, is left unsealed and is typically the top of the bag. Located at the bottom end of the bag are at least two heat seals, the first 20, a solid bottom seal, located nearer the manufacturer end, closes the bottom of the bag. The second 22, an interrupted seal, is located above the first heat seal 20 and is in contact with the interior space of the bag. The second heat seal 22 is interrupted by a vented seal gap 24. The solid bottom seal 20 and the interrupted seal 22 are substantially parallel to each other and define the vent channel 26 as the space between them. Finally, there is an exterior vent 28 to allow the air to pass from the vent channel 26 to the exterior of the bag. In the embodiment shown in FIG. 1, the exterior vent 28 takes the form of a plurality of perforation holes in both the front and rear walls of the vent channel 26. The exterior vent 28 may consist of any suitable means to allow air to escape the maze vent channel 26 to the exterior of the bag. The vented seal gap 24 should be offset from the exterior vent 28 to inhibit loss of powered or granular material contained within the bag 10.

FIG. 2 depicts an alternative embodiment with additional heat seals placed substantially perpendicular to the solid heat seal 20 and the interrupted heat seal 22 to create maze blocks 30 in the vent channel 26. The maze blocks 30 alternate in communication with either the second heat seal 22 or the first heat seal 20. Adjacent maze blocks 30 define a chamber 32 between them. The number of chambers 32 is dependent on the number of maze blocks 30 with an embodiment having multiple maze blocks 30 having a plurality of chambers 32.

An alternate embodiment, shown in FIG. 3, may be employed when it is not desirable to have a vented bag. When the contents of the bag are toxic or hazardous, it may be preferable to assure that no product escapes the bag. In this case, rupture of the bottom seal is prevented by providing a double reinforced seal as shown in FIG. 3. In this embodiment, two solid heat seals 20 are used to seal the bottom of the poly bag.

It should be understood that the maze vent is adaptable to many variations and configurations and still be within the scope of the present disclosure. As illustrative examples only, and in no way intended to limit the scope of the present disclosure, FIGS. 4 a through 4 k show multiple configurations for the maze vent. FIG. 4 a shows a poly bag 10 with a maze vent having an interrupted heat seal 22 with two vented seal gaps 24 located at either side of the seal, and the exterior vent 28 comprising a plurality of perforations located at substantially the center of the vent channel 26. FIG. 4 b shows a maze vent having an abbreviated heat seal 34. The abbreviated heat seal 34 is located between the solid heat seal 20 and the interrupted heat seal 22. The abbreviated heat seal 34 is aligned with and longer than the vented seal gap 24 so that portions of the abbreviated seal 34 are vertically aligned with portions of the interrupted heat seal 22 immediately adjacent to the vented seal gap 24. FIG. 4 c is a variation of the maze vent of FIG. 4 a with the addition of maze blocks 30 in cooperation with the interrupted heat seal 22 on either side of the exterior vent 28. FIG. 4 d is a variation of the maze vent of FIG. 4 c, adding a maze block 30 in cooperation with the solid heat seal 20 between the perforations of the exterior vent 28. FIG. 4 e shows a variation of the maze vent of FIG. 4 b, adding maze blocks 30 in cooperation with the interrupted 22 and solid 20 heat seals between the abbreviated heat seal 34 and the exterior vent 28. FIG. 4 f shows a maze vent having a substantially centered vented seal gap 24 and an abbreviated heat 34, with an exterior vent 28 on either side of the abbreviated heat seal.

FIG. 4 g is another embodiment of the maze vent, having two interrupted heat seals 22 wherein the vented seal gap 24 in each interrupted seal is located adjacent to an opposite side of the poly bag. In the embodiment of FIG. 4 g, the exterior vent 28 is vertically aligned with the vented seal gap of the innermost interrupted heat seal.

FIGS. 4 h through 4 k show embodiments of the maze vent having two interrupted heat seals 22 and no solid heat seal. The external vent, therefore, comprises a seal gap in the bottom heat seal. Instead of air being vented through the sides of the poly bag, the gap in the bottom heat seal allows air to vent out the bottom of the tubular poly bag body. FIG. 4 h shows a maze vent having two interrupted heat seals 22, with the vented seal gap 24 and the exterior vent located at opposite sides of the poly bag. FIG. 4 i shows a maze vent with an inner interrupted heat seal having two vented seal gaps 24 located at opposite ends of the heat seal and an outer interrupted seal with the exterior vent 28 located substantially in the center. FIG. 4 j shows a maze vent having an inner interrupted heat seal having a vented seal gap 24 offset to one side of the seal and an outer interrupted heat seal with two exterior vents 28 both offset to the opposite side of the poly bag as the inner seal gap. FIG. 4 k shows a maze vent with an inner interrupted heat seal having a vented seal gap 24 located substantially in the center of the inner heat seal and an outer interrupted seal with the exterior vents 28 located at opposite ends of the outer heat seal.

Additionally, the present disclosure is directed towards a method for manufacturing such a poly bag with a maze vent. The method for manufacturing a bag having a maze vent as described herein requires modification of a Windmöeller & Hölscher (W&H) Rotaliner, a machine known in the art. A W&H Rotaliner has a sealing drum housing five sealing stations. Each sealing station has a sealing bar with a first sealing surface and a second sealing surface spaced apart and substantially parallel to each other. Each sealing station makes one set of seals across the bottom of the polyethylene tube per bag. The rotating seal bar makes a series of five bags before a bar has rotated back to its original position. A notch is machined in the second sealing surface corresponding to the inner heat seal 22 creating the vented seal gap 24.

Polyethylene or other suitable material film is extruded into tubes and compressed flat forming a front wall and a rear wall. The flattened tube is then fed into the modified W&H Rotaliner wherein the first bottom heat seal 20 and the second inner heat seal 22 are made across the bottom end of the poly tube, and the exterior vent 28 is formed by making perforation holes between the seals. Perforation holes may be formed by any suitable means known in the art including mechanical or needle perforation, electrical discharge or laser. Additionally, although the perforations generally described herein as penetrating both the front and rear walls of the vent channel 26, it is also envisioned that perforations of only one wall, such as by controlled laser machining, also fall within the scope of this disclosure.

The maze blocks 30 are formed by making at least one maze block surface on the sealing bar. This is done by welding at least one bead of metal, in communication with and substantially perpendicular to either the first heat sealing surface or the second heat sealing surface. The weld bead or beads are then machined to proper dimensions. In one embodiment, the first maze block surface is in communication with and substantially perpendicular to the second heat sealing surface. The second maze block surface in communication with and substantially perpendicular to the first heat sealing surface. Additional maze block surfaces may be added, alternating in communication with the second heat sealing surface and the first heat sealing surface.

In one embodiment, the heat seals 20, 22 and the maze blocks 30 each are typically 1/16 inch wide. The solid bottom seal 20 is typically located ⅝ inch above the bottom edge 16 of the flattened poly tube. The inner seal 22 is typically located 1-⅛ inch above the bottom seal 20. The vented seal gap 24 in the inner seal 22 is typically located 3 inches from one of the side folds 12 or 14 in the poly tube and is typically ⅛ inch to ¼ inch wide. The perforation holes forming the exterior vent 28 are typically located to be centered 2 inches from the fold in the poly tube opposite the side where the vented seal gap is located.

In one embodiment having maze blocks 30, the first maze block is typically located 2 inches inward from the vented seal gap 24 and in communication with the interrupted heat seal 22. Additional maze blocks may be located typically in succession at 4 inch intervals, alternating in communication with the first heat seal 20 and the second heat seal 22. The maze blocks typically are ¾ inch long and 1/16 inch wide. However, in alternate embodiments, such as those shown in FIGS. 4 c and 4 d, maze blocks 30 may be positioned at the end of heat seal 22 directly adjacent to the vented seal gap 24.

In the disclosed embodiments, the microperforation holes forming the exterior vent 28 are typically 1 mm in diameter and located to be centered 2 inches from the side fold opposite to the vented seal gap 24 and at least ¼ inch above the solid bottom seal 20. It is envisioned that from 2 to about 10 perforations provide an optimal range for a variety of bag contents to be vented although any number of perforations may be used and still fall within the scope of the present disclosure.

After material is introduced into the poly bag 10, any trapped air is allowed to pass through the vented seal gap 24, into the vent channel 26, and is exhausted to the exterior of the bag through the exterior vent 28. Any material that passes through the vented seal gap 24 into the vent channel 26 is trapped within. In an embodiment having multiple maze blocks 30, chambers 32 are formed between adjacent maze blocks, which retain material that has entered the vent channel 26, inhibiting it from reaching the exterior vent 28.

In addition, the poly bag of the present disclosure may be incorporated as part of a multi-component flexible package. For example, multi-ply paper bags have long been known in the art. Such bags are generally formed from two or more layers of paper bonded together and folded to form a bag. One type of such bag is a “satchel bottom” type bag. A satchel bottom bag formed from multiple paper plies is folded at the bottom and secured by adhesive. When the bag is opened, the bottom is flat, allowing the bag to stand while being filled. A satchel bottom bag may be formed with or without side gussets. Satchel bottom bags may have a plastic liner for containing granulated or powdered product therein.

The poly liner having a maze vent as described herein, may be incorporated into a satchel bottom multi-ply paper bag as a bag-within-a-bag for packaging bulk granulated or powdered material. FIG. 5 shows such a satchel bottom bag 50, with a poly liner 10 disposed within a multiple ply outer tube 52. The multiple ply outer tube 52 is formed from a plurality of contiguous laterally offset plies 54, 56, and 58. The plies 54, 56, and 58 are made of a non-heat sealable material, preferably paper, such as used in well-known industrial packaging bags sold by Bemis Company, Inc. under its trademark AIRE-TITE.

The inner poly liner 10 comprises a seamless heat sealed tube, as described herein, that is fed to a bag-making device, which forms a bag blank. The inner tubular ply 10 is narrower in width than one-half the perimeter of the paper ply 58. This results in a lateral space, or gap, between the poly liner 10 and inner most paper ply 58. The tubular blank is generally designated as 60, as shown in FIG. 6, which blank may be produced on a conventional stepped end tuber device. The overlapping edges of the multiple paper plies 54, 56, 58 are adhesively bonded to form the seams along the overlaps, preferably by applying a hot melt adhesive. As the blank 60 is formed, the poly liner 10 is circumferentially bonded at 62 adjacent the top edge of the paper ply 58, which ply is the innermost contiguous paper ply. The bonds 62 are a series of dots of adhesive around the outer circumference of the poly liner 10 generally near the open end. However, below the bonds 62, the poly liner 10 is freely and non-attachably retained within the paper tube 52, except for temporary adhesive at the back side and near the bottom of the tube blank 60, which momentarily aid in the bottom folding process to form the bag. After completion of the bag, they serve no function, dissipate, and do not impede the loose folding of the bag, or its ability to be retained in a fully detachable manner within the paper plies. The paper plies 54, 56, 58 are bonded together by dots of adhesive extending circumferentially around and near the top open end of the blank 60, as shown at reference numerals 64, 66. The dots of adhesive 64 are provided to adhere ply 54 to ply 56 and dots of adhesive 66 are provided to attach ply 56 to ply 58. The line of dots of adhesive 64, 66 are also longitudinally offset front to back due to the stepping of the paper plies 54, 56, 58.

The embodiment of the open top in FIG. 5 has a stepped arrangement of the plies 54, 56, 58; however, a flush cut top, wherein the plies 54, 56, 58 are cut straight across with the top of the poly liner 10 to provide a common upper periphery, is also acceptable. Typically, a bag having flush-cut plies would be closed by sewing; however, the poly liner 10 would still be heat sealable and severable.

The closure of the open top of FIG. 5 is accomplished by reactivation of a hot melt adhesive strip 68 located on ply 56 and a hot melt adhesive strip 70 located on ply 58. The hot melt adhesive strips on the stepped front and back sides are longitudinally offset due to the stepping, so that the upper end may be passed through a folding machine, and by means of pressure rollers, the stepped plies 54, 56, 58 are overlapped and adhesively joined in a standard way as explained in U.S. Pat. No. 5,281,027.

Also, in regard to closing the top end, the upper end of the poly liner 10 would be heat sealed to closure and then, in preferred form, severed by pressure rollers applied to the exterior of the paper ply 58, whereby the poly liner 10 will detach below the line of adhesive dots 62 to result in the freely detachable arrangement of the pouch 10 as a bag-in-a-bag.

It should be understood that other types of closures are alternately envisioned for the open end of the present bag 60, including a pinch-type closure, adhesive closures other than reactivatable hot melts, or mechanical closures, such as staples, clasps, zipper assemblies, etc. The preferred form of the invention, regardless of how the paper plies are closed, envisions the heat sealing and severance of the top of the poly liner 10 so that the bag is detached thereat.

In connection with any of these types of open end closures, the formation of the satchel bottom of the bag will now be described as shown in FIGS. 6 through 10.

As previously noted, the bag blank 60 is the first step of forming the satchel bottom. FIG. 6 is the “back” side of the bag 50 for purposes of explanation. Slits are first cut through the front and back sides of exterior ply 54 whereby two parallel slits 84 are made in the front side, and two parallel slits 84 are made in the back side of ply 54. Next, two parallel slits 86 are cut through both the front and back plies 56 as shown in dashed lines in FIG. 6. In the disclosed embodiment, the slits 84 are about 3 inches long, made about 4 to 4-½ inches inwardly of the lateral edges of the bag. The slits 86 are approximately 2-½ inches long and inwardly parallel to slits 84 at about ¾ to 1 inch. The width of the bag 50 measured across the blank 60 at the outer ply 54 is standard size in the range of about 19-½ to 20 inches. Each pair of slits is cut through the bottom edge of the respective ply. These dimensions are useful for understanding the preferred embodiment, but are not to be understood as limitations to the invention. While the preferred embodiment has a non-slit innermost ply 58 and two overlying slit plies 54, 56, the invention envisions a bag 60 with from 2 to 6 paper plies overlying the ply 58; the inner ply 58 being non-slit and the others being slit wherein each ply is slit inwardly at about a ½ to 1 inch distance parallel to the slits of the preceding adjacent overlying ply. The slits are sequentially shorter by ¼ to ¾ inch less than the preceding overlying ply. The goal is to optimize the lateral distance between the slits on sequential plies so that later exposed geometric zones of adhesion surfaces are maximized for effective bonding.

A gap laterally offsets the poly liner 10 from the plies 52 by ¼ inch in the exemplary embodiment. As part of the blank forming process, the poly liner 10 is heat sealed closed along its lower edge as previously described herein, the bottom edge of the poly liner 10 being closely adjacent and parallel to the lower edge of the innermost ply 58.

As shown in FIGS. 6 and 7, a main score or crease line 72 is made transversely across the outer tube 52 and thereby across all paper plies 54, 56, 58. Also with reference to FIG. 6, in the disclosed embodiment, the main score line 72 is made about 8 inches upward from the bottom edge of the front side outer ply 54.

In FIG. 7 the satchel bottom of the bag takes on a more clearly definable form and is generally denoted by reference numeral 70. A score line 72 will become the transverse center axis of the bottom of the satchel bottom as will be understood hereinafter. Plies 54, 56, 58 are folded back with the poly liner 10 only folded to one side of the main score line 72. Thus, the poly liner 10 is retained at one side of the main score line and is tucked in triangular folds 10 a, 10 b resulting from the diagonal fold lines 74,76 of the outer tube 60.

The back of plies 54, 56, 58 are similarly arranged to create diagonal fold lines 78, 80. It will be apparent that the non-slit innermost paper ply 58 maintains a continuous lower edge generally denoted at 82. The paper plies 54, 56, 58, in addition to the poly liner 10, have the diagonal bend lines 74, 76, 78, and 80, in common, which, by virtue of the stepped arrangement of the outer tube 52 and the slits 84, 86, create various symmetric geometric exposed zones for adhesion as shown. These zones will be subsequently functional as areas of very effective adhesive mating for completing the satchel bottom 70. The blank 60 for forming the satchel bottom 70 is not symmetrical about the main score line 72 but is symmetrical about the longitudinal central axis L of the blank 60.

Secondary score lines 88, 90, which are equidistant from and parallel to the main score line 72, are shown in FIG. 8. In the disclosed embodiment, these secondary score lines 88, 90 are spaced about 3 inches to either side of the main score line 72. Since the stepping of the plies 54, 56, 58 longitudinally offsets the front and back plies (FIGS. 7 to 9), the relative upward folding of the back plies causes the folds above score line 72 to form shorter flaps than front side ply flaps below score line 72. In the disclosed embodiment, the offset of the front side to back side plies caused by the stepping of the plies 52 is about 1 inch. Thereby, when the secondary score lines 88, 90 are formed, the portion of the front side plies below score line 90 has a greater length than the back side plies above score line 88, as would be understood with reference to FIG. 7. The score lines 72, 88, 90 are all shown in FIG. 7 for purposes of explanation. It should be understood that the poly liner 10 will receive a crease along the score line 88, as well as the paper plies that envelop it.

For other embodiments, the satchel bottom is dimensioned as shown in FIG. 8. Dimension “A” represents the slit length corresponding to slits 84. Dimension “A” is dependent on the satchel bottom depth shown as dimension “C” as given by the equation A=(C+⅛ inch)−(C× 13/16), which reduces to A= 5/16 C. Dimension “B” is the distance from the bag edge to the edge of the innermost paper ply. Dimension “B” is ⅛ inch greater than the satchel bottom depth “C.” The patch length is represented by dimension “D.” Dimension “D” is given by the equation D=(W−C)+1 inch, wherein “W” is the width of the bag from one edge to the other. Dimension “D” includes 1 inch for a cuff, shown as dimension “F.” Dimension “E” is the distance from the apex to the slit as shown in FIG. 8 and is equal to dimension “A.”

The next stage in the formation of the satchel bottom 70 is illustrated in FIG. 9. An application of adhesive 92 is shown with stippling in the geometric zones of adhesion on the papers plies 54, 56, 58 created by the slitting 84, 86 and the folding of the plies about the main score line 72. As stated, this folding creates the diagonal folds 74, 76, 78, 80 whereby a very effective series of geometrically exposed opposable surface areas are created, allowing for strong contact bonding of the adhesive 92.

This formation or pattern also allows for the free non-adhesive retention of the folded poly liner 10, as shown at the broken-away triangular shaped folded portions of the paper plies (FIG. 7) that cover parts 10 a and 10 b of the poly liner. It will be seen that the poly liner 10 above score line 72 assumes a generally trapezoidal shape bounded by the score line 72, diagonal folds 74, 76, and a portion of the innermost paper ply 58, generally along the edge 94 extending between the diagonal folds 74, 76.

The adhesive 92 preferably comprises a hot melt glue and is applied in four zones as shown in FIG. 9, so as not to contact the poly liner 10. The zones are located outwardly of the secondary fold lines 88, 90 and extend to the diagonal fold lines 74, 76, 78, 80. Flaps 116, 118 formed by slitting paper plies 54 along 84 have adhesive at both flap ends, but no adhesive is applied along the length of the flap.

For bags having an easy opening feature, an opener strip 120 is placed against the diagonally folded plies 52 of the satchel bottom before the flaps 116, 118 are folded inward.

This is so that the opener strip 120 lies within the folded flaps 116, 118 of the satchel bottom 70.

The back side plies above score line 72, as shown in FIGS. 8 and 9, are rotated or folded about secondary score line 88. This step folds the back side paper plies 54, 56, 58 generally onto themselves which also rotates and secures the poly liner along the fold line 88 thereunder. At this stage, the inner poly liner 10 is folded along diagonal bends 74, 76 and at the crease formed along secondary fold line 58.

The ply flaps of the front side of the paper plies 54, 56, 58 about the secondary fold line 90, thereby rotates the adhesive 92 to overlie the paper plies 54, 56, 58 of the back side of the bag 60. This step also folds the respective portions of the front side flaps onto themselves. Each of the surfaces with reference numeral 54 indicate the exposed bottom surfaces of the satchel bottom which are comprised of the outer paper ply 54.

To further reinforce the satchel bottom, a patch 122 may be adhesively fixed to the outside of the bottom of the bag as shown in FIG. 10. The patch may be a single ply of kraft paper adhesively fixed to the exterior of the satchel bottom, or may be of other suitably strong material to reinforce the satchel bottom 70. Reinforcement may be desirable because of foreseeable rough handling or to compensate for the lack of adhesive on the flaps when combined with an easy opening feature. The patch 122 is placed on the outside of the folded flaps to reinforce the satchel bottom. The patch is secured by adhesive 124 placed in zones along the long edges of the patch. The embodiment shown in FIG. 10 has the adhesive 124 oriented in strips located on either side of the patch's long axis.

It may be desirable to have an easy-opening feature on the bag. In this embodiment, the patch has a cuff 126 located at one of its lateral side edges. The cuff 126 is defined by a pair of slits 128, 130 in the patch approximately 1 inch long. The opener strip 120 placed laterally under the flaps 116, 118 of the satchel bottom extends to cooperate with the cuff 126 area of the patch 122. The cuff area 126 is designed to allow a user to lift the cuff away from the satchel bottom 70 and grasp the opener strip 120 to pull and tear open the bottom of the bag. The opener strip 120 may be made of string, plastic or other suitable material. The opener strip 120 operates to tear the flaps 116, 118 of the satchel bottom and the patch 122 when pulled by a user to open the bag.

Upon the drying of the adhesive 92, the satchel bottom 70 is completed. The steps for forming the tube blank 60 are thereby also completed. The multi-ply plastic lined bag with satchel bottom 50 is now in a flat blank stackable form, ready for shipment to the manufacturer, packer, or the like, for filling with a product.

When the bag 10 is ready for filling, the satchel bottom 70 is unfolded to form a flat rectangular bottom shape as illustrated in FIG. 5, whereby the open mouth top is positioned for the introduction of a product, typically a dry granulated powder, such as milk granules, or the like. The short sides of the rectangular bottom are the overlapped edges of the paper plies, generally denoted at 102, 104 in FIG. 5. The longer edges of the rectangular bottom are denoted at 106, 108, which are the fold lines of the paper plies along secondary score lines 88, 90, respectively. At each corner of the bag, adjacent the short edges 102, 104, a triangle is formed with the diagonal fold lines, as at 110, 112, noted in FIG. 5. The lateral edge of the bag 50 will taper to meet the intersection of the diagonal bend lines 110, 112, shown at one side of the bag for illustration, at reference numeral 114 in FIG. 5. The mirror image of course is formed on the opposite side of the bag, not shown. 

1. A flexible polymeric package comprising: a seamless tubular body having a first end, a second end, an inner surface and an outer surface; a plurality of heat seals located proximate to said second end permanently sealing said seamless tubular body to itself creating a front panel and a rear panel; a heat sealable open mouth at said first end, wherein a receptacle is defined by said inner surface of said tubular body and said plurality of heat seals, said receptacle being configured to receive a product introduced through said open mouth and enclosing said product within said tubular body, with said open mouth being heat sealable after introduction of said product into said receptacle; said plurality of heat seals comprising at least two spaced apart, heat seals oriented transversely across said seamless tubular body proximate to said second end; said at least two spaced apart heat seals comprising an inboard heat seal positioned adjacent to said receptacle and an outboard heat seal spaced apart from said inboard heat seal and nearer said second end, wherein a channel is defined by said inboard and outboard heat seals and said front and rear panels of the seamless tubular body; and said inboard heat seal having a discontinuity, wherein said front panel and said rear panel are unattached to each other at the discontinuity allowing communication between said receptacle and said channel through the discontinuity.
 2. The flexible polymeric package of claim 1 further comprising a vent in said channel, wherein said vent allows communication between said channel and an environment outside of the package.
 3. The flexible polymeric package of claim 2 wherein said vent comprises one or more perforations in the tubular body within the channel.
 4. The flexible polymeric package of claim 2 wherein said vent comprises a plurality of perforations in the tubular body within the channel.
 5. The flexible polymeric package of claim 2 wherein said vent comprises a plurality of perforations in at least one of said front panel and said rear panel of the tubular body within said channel.
 6. The flexible polymeric package of claim 5 wherein both of said front panel and said rear panel contain perforations within the channel.
 7. The flexible polymeric package of claim 2 wherein said vent comprises a discontinuity in said outboard heat seal; said discontinuity allowing communication between said channel and said environment by way of a space between said front and said rear panel to said second end.
 8. The flexible polymeric package of claim 2 wherein said discontinuity in said inboard heat seal is located proximate to one end of said channel and said vent is located proximate to a second opposite end of said channel, whereby communication between the receptacle of said package and said environment takes place by way of the substantial length of the channel.
 9. The flexible polymeric package of claim 2 further comprising an intermediate heat seal located between said inboard and said outboard heat seal, wherein said intermediate heat seal contains one or more discontinuities and creating a tortuous path between said receptacle and said environment.
 10. The flexible polymeric package of claim 2 further comprising one or more maze blocks within said channel, wherein a maze block comprises a heat seal substantially perpendicular to one of said inboard and outboard heat seals.
 11. The flexible polymeric package of claim 10 further comprising a plurality of maze blocks perpendicular and connecting to said inboard and said outboard heat seals.
 12. The flexible polymeric package of claim 11 wherein said connection of the maze blocks to said inboard heat seal and said outboard heat seal alternates between the inboard and outboard heat seal creating a tortuous path between said receptacle and said environment.
 13. The flexible polymeric package of claim 1 comprising: an inboard heat seal positioned adjacent to said receptacle and having a discontinuity proximate to one end; an outboard heat seal spaced apart from said inboard heat seal nearer said second end, said inboard and outboard heat seals being substantially parallel to each other and oriented transversely across said seamless tubular body proximate to said second end; a channel defined by said inboard and outboard heat seals and said front and rear panels of the tubular body; and a vent in said channel located opposite of said discontinuity in said inboard heat seal, wherein a flow path is defined from said receptacle, through said discontinuity, through said channel, and out of said vent to an environment outside said package, said flow path being designed to allow passage of gaseous material out of said package and preventing passage of product out of said package while preventing ingress of moisture and other contaminants.
 14. The flexible polymeric package of claim 13 wherein said vent comprises a plurality of substantially aligned perforations in said front panel and said rear panel within the channel.
 15. A multiple ply paper bag with a polymeric liner comprising: at least two paper plies being laterally offset, each being adhesively bonded along a seam thereof forming a tube, and at least two of said paper plies being stepped relative to each other in a direction longitudinal of the bag, said tube having an open end and a closed end; a seamless inner plastic liner being attached to an innermost of said paper plies at said open end of the bag and having a width less than one half the perimeter of the innermost paper ply, said plastic liner having a plurality of heat seals at the closed end of said bag for sealing said plastic liner to itself and thereby form a plastic pouch having an interior and an exterior defined by a front panel and a rear panel, and said plastic liner further comprising a heat sealable mouth at said open end of the bag; said plurality of heat seals comprising at least two spaced apart heat seals oriented transverse to the long axis of the bag, said heat seals having an inboard heat seal positioned adjacent to the interior of the pouch and an outboard hear seal positioned proximate to the bottom of the pouch, said inboard and outboard heat seals defining a channel between said front panel and said rear panel; said inboard heat seal containing a discontinuity, wherein said front panel and said rear panel are unattached to each other at the discontinuity allowing communication between the interior of the pouch and the channel; and said closed end of said bag having a satchel bottom capable of forming a rectangular bottom of the bag when filled, said satchel bottom being formed by folds of said paper plies being folded about three fold lines, one fold line being a generally central transverse main fold along the bottom of the bag and the other two being parallel secondary fold lines equidistant from the main fold line, said innermost paper plies being non-slitted and at least one other paper ply being slitted, said folded paper ply having means to form geometric zones of adhesion, an adhesive on said zones for securing said folded paper plies together, said inner plastic liner being detachably and non-adhesively retained at said satchel bottom, and the plastic pouch being folded about said main fold line and one of said two secondary fold lines.
 16. The bag of claim 15 wherein said pouch contains a vent within said channel creating a flow path from the pouch interior through the discontinuity in the inboard heat seal, through the channel, and through the vent to the exterior of the pouch.
 17. The bag of claim 16 wherein said discontinuity in said inboard heat seal is located proximate to one of the lateral sides of the pouch and said vent is located proximate to an opposite lateral side of the pouch.
 18. The bag of claim 16 wherein said vent comprises one or more perforations in at least one of said front panel and said rear panel within the channel.
 19. The bag of claim 17 wherein said vent comprises a plurality of perforations in said front panel and said rear panel within the channel.
 20. The bag of claim 18 wherein said vent is comprised of 2 to 10 perforations.
 21. The bag of claim 18 further comprising one or more maze blocks within said channel, wherein a maze block comprises a heat seal substantially perpendicular to one of said inboard and outboard heat seals.
 22. The bag of claim 21 further comprising a plurality of maze blocks perpendicular and connecting to said inboard and said outboard heat seals.
 23. The bag of claim 22 wherein said connection of the maze blocks to said inboard heat seal and said outboard heat seal alternates between the inboard and outboard heat seal creating a tortuous path between said interior and exterior of the pouch.
 24. The bag of claim 17 further comprising a reinforcing patch affixed to the outside of said satchel bottom over the folds of the outer paper ply.
 25. The bag of claim 24 wherein said reinforcing patch comprises at least one ply of kraft paper adhesively affixed to the outside of the satchel bottom.
 26. The bag of claim 24 further comprising an easy-open apparatus, said easy-open apparatus comprising an opener strip located within the folds of the satchel bottom extending transversely outward from the folds of the satchel bottom to cooperate with said reinforcing patch, said reinforcing patch having a cuff defined by a pair of spaced apart substantially parallel slits at one edge of the patch, said opener strip attached to said cuff allowing a user to pull said cuff and opener strip thereby tearing said patch and paper plies of said underlying satchel bottom folds allowing the user to open the satchel bottom to access the plastic liner.
 27. The bag of claim 26 wherein said opener strip is made of plastic.
 28. A multiple ply paper bag with a polymeric liner comprising: at least two paper plies being laterally offset, each being adhesively bonded along a seam thereof forming a tube, and at least two of said paper plies being stepped relative to each other in a direction longitudinal of the bag, said tube having an open end and a closed end; a seamless inner plastic liner being attached to an innermost of said paper plies at said open end of the bag and having a width less than one half the perimeter of the innermost paper ply, said plastic liner further comprising a plurality of heat seals at the closed end of said bag for sealing said plastic liner to itself and thereby form a plastic pouch having an interior and an exterior defined by a front panel and a rear panel, and said plastic liner further comprising a heat sealable mouth at said open end of the bag; said plurality of heat seals further comprising an inboard heat seal located adjacent to the interior of said pouch having a discontinuity in said inboard heat seal proximate to a first lateral side edge of the pouch, and an outboard heat seal spaced apart and substantially parallel to the inboard seal; a channel located between said inboard and outboard heat seals and defined by said front and rear panels; a vent in said channel comprising a plurality of perforations in at least one of said front panel and rear panel within the channel, said vent located proximate to a second lateral side edge opposite that of said first lateral side edge, wherein gaseous contents of said pouch interior is allowed to flow through the discontinuity of the inboard heat seal, through the channel, and out the vent to the exterior of the pouch while restricting flow of product out of the pouch and restricting flow of moisture and other contaminants into the pouch; said closed end of said bag having a satchel bottom capable of forming a rectangular bottom of the bag when filled, said satchel bottom being formed by folds of said paper plies being folded about three fold lines, one fold line being a generally central transverse main fold along the bottom of the bag and the other two being parallel secondary fold lines equidistant from the main fold line, said innermost paper plies being non-slitted and at least one other paper ply being slitted, said folded paper ply having means to form geometric zones of adhesion, an adhesive on said zones for securing said folded paper plies together, said inner plastic liner being detachably and non-adhesively retained at said satchel bottom, and the plastic pouch being folded about said main fold line and one of said two secondary fold lines a reinforcing patch adhesively affixed to the outer paper ply wherein said reinforcing patch comprises at least one ply of kraft paper.
 29. The bag of claim 28 further comprising an easy-open apparatus, said easy-open apparatus comprising an opener strip located within the folds of the satchel bottom extending transversely outward from the folds of the satchel bottom to cooperate with said reinforcing patch, said reinforcing patch having a cuff defined by a pair of spaced apart substantially parallel slits at one edge of the patch, said opener strip attached to said cuff allowing a user to pull said cuff and opener strip thereby tearing said patch and paper plies of said underlying satchel bottom folds allowing the user to open the satchel bottom to access the plastic liner.
 30. A method of forming a multiple ply paper bag with a polymeric liner comprising the steps of: extruding a seamless polymeric tube; cutting said polymeric tube to a desired length and thereby defining a longitudinal axis, said polymeric tube having an interior surface, an exterior surface, a first end and a second end; sealing the second end of said polymeric tube with a plurality of heat seals oriented transverse to said longitudinal axis, said plurality of heat seals and said interior surface thereby defining a receptacle configured to receive a product, said plurality of heat seals having at least an inboard heat seal located adjacent said receptacle and an outboard heat seal spaced apart from said inboard seal, wherein a channel is defined between said inboard heat seal and said outboard heat seal and a front panel and a rear panel, and wherein said inboard heat seal contains a discontinuity such that said receptacle is in communication with said channel through the discontinuity; providing a plurality of offset paper plies, said paper plies comprising at least an outermost paper ply and an innermost paper ply, said paper plies being folded such that each of said plies is bonded to itself forming a multi-ply paper tube with a seam for each ply, said seams being laterally offset thereby spacing seams for each layer about the bag, said tube having a first end and a second end; bonding said first end of said polymeric tube to said first end of the innermost ply of said multi-ply paper tube; folding opposing corners at said second end of said multi-ply paper tube inward creating a pair of diagonal fold lines, each diagonal fold line extending from a lateral side edge of said multi-ply paper tube and defining a front flap and a rear flap, whereby said polymeric tube is folded within said rear flap folds and is freely and non-attachably retained; applying adhesive to said front and rear flaps and folding said front and rear to close said second end of said multi-ply paper tube thereby forming a satchel bottom.
 31. The method of forming a multiple ply paper bag with a polymeric liner of claim 30 further comprising the step of: providing a vent in said channel thereby creating a flow path whereby gaseous material may pass from said receptacle through said discontinuity in said inboard heat seal, pass through said channel through said vent to an environment outside said polymeric liner.
 32. The method of forming a multiple ply paper bag with a polymeric liner of claim 31 further comprising the step of: perforating at least one of said front panel and said rear panel of said channel thereby forming a vent.
 33. The method of forming a multiple ply paper bag with a polymeric liner of claim 31 further comprising the step of: perforating both said front panel and said rear panel of said channel thereby forming a vent. 